1. Field of the Invention
The present invention relates to a resource reservation management apparatus used in an AV network, where AV apparatuses are connected, for transferring data streams among the AV apparatuses.
2. Related Art of the Invention
A resource management apparatus of the prior art will be described below with reference to accompanying drawings, taking an isochronous resource manager of the IEEE1394 standard.
FIG. 8 shows the constitution of the resource management apparatus of the prior art. In FIG. 8, reference numeral 801 denotes the resource management apparatus, 802 denotes a frequency band management table, 803 denotes a channel management table, 804 denotes a controller and 805 denotes a communication interface.
The resource management apparatus 801 performs a function of managing network resources to ensure correct transmission of AV data stream. FIG. 9 shows an example of the AV network constitution provided with the resource management apparatus 801.
The resource management apparatus 801 of the prior art does not perform prospective resource management that takes into account future events. That is, upon receipt of a frequency band allocation request from a user, the resource management apparatus 801 checks frequency bands currently not in use stored in the frequency band resource management table 802, and compares them with the requested frequency band. In case the frequency band can be allocated, the controller 804 notifies the user of the permission of allocation, while the frequency band resource management table 802 is updated at the same time.
Upon receipt of a channel allocation request, on the other hand, the channel management table 803 is checked for an unused channel registered therein, with an available channel being notified to the user and the channel management table 803 being updated.
The user transfers the AV data stream using the assigned channel within the frequency band permitted.
In FIG. 9, reference numeral 901 denotes the resource management apparatus 801, 902 denotes a set-top box (hereinafter STB), 903 denotes a video cassette recorder (hereinafter VCR) and 904 denotes an AV data stream.
When video recording of a digital broadcast program received with the STB 902 by means of the VCR 903 is to be reserved, the resource management apparatus 901 starts by retrieving program starting/ending time information from an electronic program guide (hereinafter EPG).
When the reservation start time comes, the STB 902 acquires a currently available network resource that is monitored by the resource management apparatus 901, for the first time as described above, and sends an AV data stream 904 from the STB 902 using an isochronous packet.
Then the VCR 903 is enabled to receive and record the AV data stream 904.
However, there has been such problems as described below with the constitution described above.
When a user (A) reserves at 10:00 a.m. video recording for time period of 8:00 to 10:00 p.m. and another user(B) reserves at 11:00 a.m. video recording for time period of 7:00 to 9:00 p.m., the video recording of the user(B) is performed at 7:00 to 9:00 p.m. to consume full frequency band, and therefore the video recording for the user(A) can not be performed. That is user(A) who reserved before the user (B) can not record on account of the user(B) who reserved after the user(A).